1. Field of the Invention
The present invention relates to an apparatus for controlling a group of elevator cars, and more particularly to an apparatus and method for controlling a group of elevator cars wherein one of plural separate elevator car controllers controls all the elevator cars within the group, without being provided with an extra car group controller and at this time the other car controllers are backed up for data related to controlling the group of elevator cars so that when an error occurs in an elevator car controller another car controller can succeed to take control from the problem car controller, thereby improving system stability.
2. Description of the Prior Art
In general, multi-story buildings are furnished with a plurality of elevator cars which require to employ a system for efficiently controlling the cars.
A car group control system systematically organizes a plurality of elevator cars using a sophisticated microcomputer and a communication link to provide quality service to hall and cage passengers. That is, when there occurs a hall call, the system serves to allocate an optimally selected car to the hall passengers by estimating a variety of factors such as location, speed, direction, door closing status, possible number of additional passengers and the like.
To decrease a waiting time of hall passengers while maximizing the carriage capacity of elevator cars, and to save energy, an elevator car control system employs a method in which a new hall call is allocated to a selected elevator car.
In such a conventional system for controlling a plurality of elevator cars, an extra apparatus is provided to improve the service quality and efficiency so that a double structured system including an extra apparatus is employed to prevent a breakdown which may result from the attached apparatus. However, such a double structured apparatus incurs an increased production and maintenance costs.
As shown in FIG. 1 illustrating a conventional system for controlling a group of elevator cars, a car controller 100B controls a car 107 and a motor 108. A multi-controller 100A collects data from the car controller 100B to perform an overall control over a group of elevator cars. That is, the car controller 100B collects and sends to the multi-controller 100A data including a present location, a door open/close status, switch modes, a hall call and a cage call of the car 107.
A data collector 104 in the multi-controller 101A collects data including the car status, number of passengers, number of hall calls, door open time and the like. A data processor 103 determines a required traffic amount and recognizes a peak traffic in accordance with the collected data.
A data generator 101 generates data required for allocation. A control unit 102 allocates an elevator car judged to be most appropriate to a present hall call, in accordance with a control program which takes into consideration the data generated in the control unit 102, and when the collected data indicates an error the car operation is halted accordingly.
The multi-controller 101A is controlled by a microcomputer, and a problem occurring in the microcomputer may lead to a deteriorated function and reliability of the entire system, so that to prevent such a problem there are provided, as shown in FIG. 2, a first microcomputer 211 for carrying out a multi-controlling and a second microcomputer 212 having the same function as the first microcomputer 211 and backing up data required to perform a multi-controlling, whereby when there occurs a breakdown in the first microcomputer 211 the backup microcomputer 212 takes over the multi-controlling instead.
As shown in FIG. 2, the conventional multi-controlling system having a double structure includes: a plurality of car controllers 220A-220N; a group controller 211 for carrying out a multi-controlling while communicating with each of the car controllers 220A-220N using a communication link; and a backup unit 212 for periodically receiving and temporarily retaining multi-controlling data from the group controller 211 and carrying out a car group controlling when there occurs an error in the group controller 211.
Each of the plurality of car controllers 220A-220N is composed of a corresponding one of CPUs 221A-221N, a corresponding one of ROMs 223A-223N for storing therein the car program, and a corresponding one of RAMs 222A-222N for storing therein data processed in the CPUs 221A-221N.
The operation of the thusly constituted conventional multi-elevator controlling apparatus will now be described.
The car controllers 220A-220N respectively transmit data related to car calls and driving states to the group controller 211 which in turn performs a group management program based upon the input data so that an optimal driving mode or allocation order mode value is transmitted to the respective car controllers 220A-220N.
While performing the group management program, the backup unit 212 periodically receives and stores therein the required data from the group controller 211.
When a malfunction occurs in the group controller 211, the backup unit 212 carries out a group management control based upon the data stored therein, whereby regardless of an error occurring in a group management controller the car group can be continuously controlled by another group management controller.
However, a breakdown in the backup unit 212 makes it difficult to carry out further group management control.
In a building equipped with a plurality of elevator cars, a pair or more of the cars out of the entire number of cars are formed into several groups, and each of the groups performs an independent group management control, and also because a double structural group management system has a fixed mechanical structure, it has been difficult to change a group from one to another and to carry out an independent management over the groups.
Further, employing an extra backup apparatus for group management has led to a cost increase so that when there are provided two or three elevator cars an elevator group management system is excluded and instead there is applied a parallel control technique of the elevator cars. That is, a plurality of parallel furnished elevator cars are connected to each other by a communication line, and through the communication lines the state of the other cars, i.e., their location and direction, is detected and a hall call is selected by itself. At this time, in the hall call selecting method, a car controller in charge of a selected section allocates a hall call to a respective car.
However, such an operation in accordance with a parallel driving method suffers a decreased functionality compared to a group control system which carries out an optimal allocation in consideration of all the serviceable floors and all the hall and cage calls.